Nitro-substituted alkyl ester-stabilized adhesive compositions



FIP8501.

United States Patent Our invention relates to adhesive compositions. More particularly our invention relates to adhesive compositions stabilized against attack by microorganisms.

Adhesive compositions are made from a wide variety of materials and have many and varied applications. Generally most adhesives are separated into three main categories: those which are of an animal origin such as the animal glues, the fish glues, and the casein pastes; those of vegetable origin such as the gums, the starch adhesives, the dextrin adhesives, the rubber latex adhesives, and the natural resin adhesives; and the synthetic adhesives such as the synthetic resins, for example, those of the ureaformaldehyde, phenol-formaldehyde, acrylic, and vinyl types. All such adhesives possess one common property, the ability to enable surfaces to merge on contact or under pressure and after merger, resist separation.

A common problem of adhesive compositions is their lack of resistance to attack by certain microorganisms during storage. On certain of the widely used types of adhesives, particularly casein adhesives and starch adhesives, spoilage takes place in a matter of days. Such spoilage, which can finally cause coagulation and even separation of the adhesive, is easily observed by the formation of mold and the production of highly noxious odors.

We have now discovered a means whereby adhesive compositions can be made resistant to spoilage. Our new adhesive compositions even retain this resistance after long storage periods. Thus, our stabilized adhesive compositions are not only effective in preventing mold formation and noxious odors but successfully inhibit decomposition, coagulation and separation of the adhesive composition itself.

Our adhesive compositions are produced by incorporating a stabilizing amount of a nitro-substituted alkylester prepared by the condensation of a lower nitroalka- 1101 with a diabasic or tribasic acid in the presence of an acid catalyst. In preparing the nitro substituted alkylesters by condensation of a lower nitroalkanol with a dibasic or tribasic acid, it is preferable to first form a benzene solution of the acid and the nitroalcohol using approximately a excess of the theoretically reactant amount of the nitroalcohol, reflux the said solution in the presence of an acid catalyst such as sulfuric acid or paratoluene sulfonic acid until the final product is formed in the reaction mixture. The product is then recovered from the reaction mixture by subsequently cooling, washing, and concentrating the mixture to obtain the desired product.

Examples of suitable nitro-substituted alkylesters coming within the scope of our invention are bis(2-nitrobutyl) adipate, tris(2-nitrobutyl) citrate, bis(2-nitropropyl) succinate, bis(2-nitrobutyl) tartrate, etc., and the like.

The amount of nitro-substituted alkylester necessary to stabilize adhesive compositions will naturally vary depending in the main on the particular adhesive to be stabilized and the conditions of storage. Usually, however, amounts as low as 100 ppm. by weight based on the weight of the adhesive compositions are effective in controlling spoilage. Generally we have found that it is not necessary to exceed 1,000 ppm. of our stabilizing agents in the adhesive compositions. Under most cir- REFEREEQCE cumstances satisfactory results are obtained when 250 ppm. to 500 ppm. of our stabilizers are utilized.

The following examples further illustrate our invention, but we do not intend to be limited to the procedures, types of adhesives, or amounts of nitro-substituted alkylesters set out therein. Inclusion of all equivalents obvious to the art is intended.

EXAMPLE I To test the effectiveness of our nitro-substituted alkylesters in preserving adhesive compositions, a casein adhesive composition containing grams casein, 7 mls. of a 29% ammonia solution, and 623 mls. of water was divided into 5 equal portions. A nitro-substituted alkylester stabilizing agent was added to 4 of the 5 portions and the remaining portion was used as a control. Each of the 5 portions was then inoculated with a mold found growing in a casein-adhesive composition. Each of the 5 portions was then placed in a separate open jar and allowed to stand for 30 days. The following table shows the results of the 30-day test.

EXAMPLE II The procedure of Example I was followed with the exception that a polyvinyl alcohol starch adhesive containing 35 grams polyvinyl alcohol, 70 grams corn starch, and 525 mls. water was utilized instead of the casein adhesive of Example I. The following table shows the results of this test.

Table II Amount of nitro-sub- Mold Portion Nitro-substituted alkylester stituted Formation alkylester, p.p.m.

Bis(2nltrobutyl) adipate 600 None. Tris(2-nitrobutyl) citrate 1,000 None. Bis(2-nitropropyl)succinate 250 None. Bis(2-nitrobutyl) tartrate 1,000 None.

Control Covered Sample.

SEARCH R00l EXAMPLE III An adhesive composed of 24 kilograms dextrin, 24 liters of water, and 10 grams of ginger grass oil was effectively stabilized by bis(Z-nitrobutyl) adipate.

EXAMPLE IV EXAMPLE V An adhesive composition composed of grams of glue, 100 mls. of water, 5 grams of glycerin, and 3 grams of potassium bichromate was effectively stabilized by bis(2-nitrobutyl) tartrate.

3 EXAMPLE VI An adhesive composition composed of 17 pounds castor oil, 100 pounds pine resin, and 50 pounds denatured alcohol was effectively stabilized by bis(2-nitropropyl) succinate.

Now having described our invention, what we claim 1. An adhesive composition stabilized against microorganism attack which comprises an adhesive selected from the group consisting of casein adhesive, starch adhesive, glue adhesive and rubber latex adhesive and a stabilizing amount of a nitro-substituted alkylester formed from the condensation of lower nitroalkanols and alkyl carboxylic acids selected from the group consisting of dibasic and tribasic acids having up to and including 6 carbon atoms.

2. The composition of claim 1 wherein the adhesive is a casein adhesive.

3. The composition of claim 1 wherein the adhesive is a starch adhesive.

4. The composition of claim 1 wherein the adhesive is a glue adhesive.

5. The composition of claim 1 wherein the adhesive is a rubber latex adhesive.

6. An adhesive composition stabilized against microorganism attack which comprises an adhesive selected from the group consisting of casein adhesive, starch adhesive, glue adhesive and rubber latex adhesive and from about 100 to about 1,000 p.p.m. of a nitro-substituted alkylester formed from the condensation of lower nitroalkanols and alkyl carboxylic acids selected from the group consisting of dibasic and tribasic acids having up to and including 6 carbon atoms.

7. An adhesive composition stabilized against microorganism attack which comprises an adhesive selected from the group consisting of casein adhesive, starch adhesive, glue adhesive and rubber latex adhesive and from about 250 to about 500 p.p.m. of a nitro-substituted alkylester formed from the condensation of lower nitroalkanols and alkyl carboxylic acids selected from the group consisting of dibasic and tribacis acids having up to and including 6 carbon atoms.

8. The composition of claim 7 wherein the nitro-substituted alkylester is bis(2-nitrobutyl) adipate.

9. The composition of claim 7 wherein the nitro-substituted alkylester is tris(2-nitrobutyl) citrate.

10. The composition of claim 7 wherein the nitro-substituted alkylester is bis(Z-nitropropyl) succinate.

11. The composition of claim 7 wherein the nitro-substituted alkylester is bis(Z-nitrobutyl) tartrate.

References Cited by the Examiner UNITED STATES PATENTS 1,925,819 9/1933 Putnam et al 106-125 2,727,012 12/ 1955 Treat et al 26029.7 2,888,422 5/1959 Johnson et a1 260-297 2,976,236 3/1961 Bennett et al 167-22 2,979,455 4/1961 Bennett et al 16722 3,001,935 9/1961 Bennet et a1. 16722 3,058,835 10/1962 Sheeran 106-146 ROBERT F. WHITE, Primary Examiner.

MORRIS LIEBMAN, ALEXANDER BRODMERKEL,

Examiners. 

1. AN ADHESIVE COMPOSITION STABILIZED AGAINST MICROORGANISM ATTACK WHICH COMPRISES AN ADHESIVE SELECTED FROM THE GROUP CONSISTING OF CASEIN ADHESIVE, STARCH ADHESIVE, GLUE ADHESIVE AND RUBBER LATEX ADHESIVE AND A STABILIZING AMOUNT OF A NITRO-SUBSTITUTED ALKYLESTER FORMED FROM THE CONDENSATION OF LOWER NITROALKANOLS AND ALKYL CARBOXYLIC ACIDS SELECTED FROM THE GROUP CONSISTING OF DIBASIC AND TRIBASIC ACIDS HAVING UP TO AND INCLUDING 6 CARBON ATOMS. 